Shoe sole and cushion for a shoe sole

ABSTRACT

The present invention relates to a cushion ( 20 ) for use in a shoe sole. The cushion ( 20 ) includes a medial chamber ( 26 ) for cushioning a medial portion of a wearer&#39;s foot, an internal chamber ( 40 ) disposed within the medial chamber ( 26 ) to increase a stiffness of the medial chamber, and at least one lateral chamber ( 24 ) for cushioning a lateral portion of the wearer&#39;s foot. The medial chamber ( 26 ) and lateral chamber ( 24 ) may be of unitary construction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application of international PCTapplication Ser. No. PCT/US03/00317 filed under 35 U.S.C. §371 on Jan.6, 2003 and published on Jul. 17, 2003 as International Publication No.WO 03/056964, and claims priority under 35 U.S.C. §363 and 35 U.S.C.§119 to U.S. provisional patent application Ser. No. 60/344,341, filedon Jan. 4, 2002, each of which is incorporated in its entirety herein byreference thereto.

FIELD OF THE INVENTION

The present invention relates to a cushion for use in a shoe sole forcushioning and supporting a foot. More particularly, the inventionrelates to a cushion that has at least one chamber that encloses aninner chamber for cushioning a region of a foot.

BACKGROUND OF THE INVENTION

Athletic shoe soles have been made with a variety of resilientcushioning elements for cushioning a wearer's feet, such as by storingand absorbing impact energy. Known cushioning elements include bladdersenclosing material that is pressurized, such as to a pressure greaterthan the ambient pressure surrounding the cushioning element. Typicalmaterials include gases, viscous liquids, and gels. The cushioningproperties of these known shoe soles depend upon retaining thepressurized state of the enclosed material.

A cushion element for a shoe sole would ideally provide cushioningproperties that vary as a function of position. For example, a cushionproviding a stiffness that is greater along a medial edge relative to alateral edge would tend to reduce pronation compared to a cushionlacking such differential stiffness.

SUMMARY OF THE INVENTION

The present invention relates to a cushion that includes at least onechamber enclosing an internal element. A chamber is an element having asurface that encloses a volume, such as a hollow volume containing a gasor fluid. The internal element is preferably a blow molded chamber thatincreases the vertical stiffness and spring of the enclosing chamber.The chamber that encloses the internal chamber may be referred to as amedial chamber because it is preferably disposed along a medial portionof the cushion. When the cushion is disposed in a shoe sole, theenclosing chamber preferably extends from a position adjacent the medialheel portion of the shoe sole to a location adjacent the medial forefootportion of the shoe sole.

The medial chamber and internal element have a strength and stiffnesssufficient to support the medial (inner) edge portion of a wearer's footeven in the absence of any fluid trapped therein. Thus, the cushioningproperties of the medial chamber and internal element are preferablysubstantially independent of the pressure or compressibility of anyfluid or other material present therein.

In addition to the medial chamber, the cushion preferably includes atleast one lateral cushion and one rear cushion. When the cushion isdisposed in a shoe sole, the lateral cushion supports and cushions alateral (outer) edge portion of a wearer's foot. The rear cushionsupports and cushions the rear of a wearer's foot, such as the back ofthe heel.

The lateral and rear cushions preferably enclose a fluid, which may flowbetween these cushions by a tube or other passage therebetween. Thecushioning properties of the lateral and rear cushions may vary during aheel strike as compression by a wearer's foot causes fluid to flow fromthe rear chamber to the lateral chamber. The fluid is preferably a gas,such as air. Prior to heel strike, any fluid trapped within the lateraland rear chambers is preferably not pressurized to a pressure greaterthan the ambient pressure surrounding the cushion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is discussed below in relation to the drawings inwhich:

FIG. 1 shows a bottom view of a cushion of the invention;

FIG. 2 shows a cross sectional view of the cushion of FIG. 1;

FIG. 3 shows a second cross sectional view of the cushion of FIG. 1;

FIG. 4 shows a lateral side view of the cushion of FIG. 1;

FIG. 5 shows a medial side view of the cushion of FIG. 1;

FIG. 6 shows a bottom view of a second embodiment of a cushion accordingto the invention;

FIG. 7 shows a cross sectional view of the cushion of FIG. 6;

FIG. 8 shows a medial side view of a shoe sole and cushion of theinvention;

FIG. 9 shows a bottom view of the sole of FIG. 8;

FIGS. 10 and 11 show cross sectional views of the shoe sole of FIG. 9;

FIG. 12 shows a bottom view of second shoe sole and cushion of theinvention;

FIG. 13 shows a cross sectional view of the shoe sole and cushion ofFIG. 12;

FIG. 14 shows a lateral view of the shoe sole and cushion of FIG. 12;and

FIG. 15 shows a medial view of the shoe sole and cushion of FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a cushion 20 includes an outer cushion 22,which preferably includes a lateral chamber 24, a medial chamber 26 anda rear chamber 28. Chambers 24, 26, 28 may contain a fluid, such as agas, which, in the resting state, is preferably not pressurized to apressure greater than the ambient pressure surrounding cushion 22 duringuse. Preferably, the strength of the chambers is sufficient forsupporting and cushioning the wearer's foot irrespective of any materialcontained therein. It should be understood, however, that one or more ofthe chambers may include a fluid that cooperates with the chamber tosupport and cushion a wearer's foot. For example, a chamber may enclosea gas that increases in pressure during a heel strike to provide furthercushioning to a wearer's foot.

Cushion 20 is preferably disposed in shoe sole formed of conventionalmaterials. For example, the sole may include a main sole formed of ethylvinyl acetate (EVA) and an outsole formed from a material such asrubber. Suitable soles and sole constructions for use with cushion 20 isdiscussed in U.S. Pat. No. 6,026,593, which is incorporated by referenceherein. In a preferred embodiment, cushion 20 is disposed within a soleto cushion a wearer's heel.

The footprint of the cushion 20 is preferably asymmetric. The medialchamber 26 preferably extends a distance d₁ further toward the front ofthe cushion (i.e., the front of the shoe when placed in a sole) than thelateral chamber. The asymmetry enhances the ability of cushion 20 toreduce the tendency of a wearer's foot to pronate.

The width w₁ of the medial chamber is defined by the outer medial edge50 of the cushion 20 and an inner medial edge 52 that runs substantiallyparallel with the outer medial edge parallel to the major longitudinalaxis 54 of the cushion. The width of the medial chamber is preferablyless than about 40% of the total width w₂ of the cushion 20. When thecushion 20 is disposed in the sole of a shoe, the medial chamberpreferably extends from a point adjacent the heel to the forefoot of theshoe. The medial chamber preferably has a width to height aspect ratioof between about 2 and about 4.

The medial and lateral chambers are preferably spaced apart by a web 42,which allows the medial and lateral chambers to compress independentlyof one another. Web 42 also allows cushion 20 to flex about alongitudinal axis of web 42. The rear chamber is spaced apart from themedial and lateral chambers by a web 43, which allows the rear chamberto compress independently of the medial and lateral chambers. Web 43also spaces a rear portion 75 of medial chamber 26 apart from chamber28.

Medial chamber 26 encloses an internal element 40, which is preferably ablow molded chamber. Internal element 40 and medial chamber 26 cooperateto make the medial portion of cushion 20 stiffer than the lateralchambers for stabilizing the wearer's foot to thereby prevent thewearer's foot from over-pronating towards the lateral direction. Thestiffness of the medial chamber with internal element is preferably atleast about 10% greater, such as about 25% greater, than the stiffnessof the lateral chamber.

The medial chamber and internal element stiffness can be modified by,for example, changing the radii r₁ of the chamber walls adjoining thetop and bottom surfaces. For example, decreasing the radii increases thestiffness of the medial chamber or internal element. Increasing thefootprint of the medial chamber relative to the surface area of theupper surface of the chamber also increases the stiffness of thechamber.

Other approaches for modifying the stiffness of a chamber include addingribs 56 to the surfaces of the chamber, adding pinch/locator pin marks58 and increasing the stiffness of the internal component. The marks 58may be used to prevent the internal chamber from moving within themedial chamber. In this case, the marks 58 are formed as depressionsextending from an outer surface 60 of medial chamber to an outer surface62 of inner element 40.

The shape and construction of the lateral chambers and any internalelements therein are selected in order to make these chambers morecompliant than the combined medial chamber/internal element forcushioning the wearer's foot. For example, the lateral chambers arepreferably formed without an internal element or formed with an internalelement that is more compliant than that used within the medial chamber.Additionally, the radii r₂ adjoining the walls and top surface may begreater than the corresponding radii of the medial chamber. The lateralchambers may be shaped with a relatively smaller footprint to topsurface ratio than the medial chamber.

The lateral chambers may be fluidly connected such as by a tube 77 toallow fluid to flow between the lateral chambers during heel strike. Asfluid flows from one chamber to another during heel strike, thecushioning properties of the chamber receiving the fluid increase. Thecushioning properties of the medial chamber, however, are preferablyindependent of the cushioning properties of the lateral chambers. Thus,the medial chamber is preferably not fluidly connected with the lateralchambers.

Outer surface 62 of internal element 40 preferably correspondssubstantially in shape to and is of a similar size as an internalsurface 63 of medial chamber 26. Where the external surface of theinternal element is of a smaller size or different shape than theinternal surface of the medial chamber, the inner surfaces, preferablythe top and bottom inner surfaces, of the medial chamber may contain oneor more locator cavities to position the inner cushioning elementtherein. The outer surface of the inner cushioning element may containone or more protrusions of complementary shape to the locator cavities.Of course, the inner surface of the medial chamber may be provided withprotrusions complementary to cavities of the outer surface of the innercushioning element.

Referring to FIGS. 3 and 4, the bottom surface 66 of the rear chamber ispreferably formed at an angle φ to the upper surface 68 of the rearchamber 28 thereby creating a beveled surface. Angle φ is between about3 and 15 degrees, such as between about 6 and 10 degrees. Preferably thedistance between the top and bottom surfaces of the rear chamberincreases moving from the rear of the cushion towards the front of thecushion so that the bottom surface slopes up from the horizontal to meetthe top surface.

The rear chamber is disposed at an angle from the centerline of cushion20 and is separated from the nearest lateral and medial chambers inorder to form a heel cleft, which follows web 43. The angle fromcenterline is about 20 to 45 degrees, such as about 30 to 40 degrees.During heel strike, cushion 20 flexes along the heel cleft reducingtendency of the shoe to roll excessively to one side. Following a heelstrike, the heel cleft reduces the rate of pronation to reduce theamount of pronation that occurs between heel strike and when theforefoot contacts a surface.

In one embodiment of the invention, an outsole is adhered directly tolower surfaces of chambers 24, 26, and 28 leaving webs 42 and 43exposed. Leaving the webs exposed allows the completed shoe sole toretain more of the cushion's flexibility along webs 42 and 43.

Referring to FIGS. 1, 4, and 5, the walls of the outer cushion 22 mayhave ribs 56 extending partially or substantially fully widthwisethereacross. The ribs are configured and dimensioned for increasing wallstiffness. For example, the ribs may extend across the top and bottomsurfaces of the component to increase the stiffness of the component.

Outer cushion 22 is preferably blow molded in a single piece of unitaryconstruction. As understood in the art, blow-molding may includeextrusion of a material resin through a die and mandrel, injection ofair through the resin, followed by closure of the mold, cooling andrelease of the molded element.

Inner element 40 is also preferably blow molded but may also be formedby a different process than the outer cushion 22.

Outer cushion 22 is preferably formed of a material having a lowermodulus than the material forming inner element 40. The material formingthe outer cushion preferably provides dampening properties to cushion20. For example, preferred materials for the outer cushion 22 includethermoplastics such as urethane (and blends), PVC (and blends),polyester and polyester-polyether glycol blends, ethylene vinyl acetateand polyether.

The material forming the inner element 40 preferably imparts stiffnessand spring properties to cushion 20. Preferred materials for use in theconstruction of inner element 40 of cushion 20 include, for example,polyester elastomers such as HYTREL HTR5612 or HTX8382, urethane (andblends), PVC (and blends), polyester and polyester-polyether glycolblends, ethylene vinyl acetate and polyether. The HYTREL elastomersdesigned for blow molding and sold by Dupont. The inner element 40 mayalso be formed, for example, of a foam, such as a closed cell foam toprovide a light weight dampener.

Preferred elastomeric materials for forming inner element 40 haverelatively high melt viscosities. The most preferred inner elementmaterial preferably has a Poisson's ratio of about 0.45, a flexuralmodulus of between about 100 and about 150 MPa, for example 124 MPa, anda hardness durometer of between about 40 and 60, for example 50 on the Dscale. When subjected to a compression test in which the material iscompressed to 50% of its original thickness for 48 hours and thenreleased, the material preferably decompresses substantially completely.The preferred configuration returns to within 1% of its originalthickness after a compression test.

Using the preferred materials, the preferred thickness 30 of the wallsof the outer cushion 22 is between about 1.0 to 2.5 mm, such as about1.4 mm to 2.4 mm to support and cushion the heel together with theremainder of the sole without collapsing. The thickness 31 of the wallsof the internal element 40 is preferably between about 0.5 to 2.2 mm,such as about 0.75 to 1.5 mm. These thickness can be decreased orincreased depending on the activity for which the shoe is built. Thethickness may also be varied in from chamber to chamber to localizevariations in stiffness. For example, the thickness may be reduced whenthe surface geometry of the chambers is modified, such as by addingribs, to increase the chamber strength compared to an unmodifiedchamber. The preferred height 32 of the outer cushion is between about60% and 95% of the height of the sole at the cushion, and mostpreferably between about 80% and 85%.

As a result of the preferred blow molding process, stubs 34 may remainthrough which air was blown during manufacturing. These stubs may besealed to prevent the cushion 20 from emitting an annoying noise eachtime a step is taken, as air is sucked in and blown out through thestub. Sealing the stubs 34 also prevents water, or other fluids that maybe present on a walking surface from entering the cushion 20. If thestubs 34 themselves are not closed, material adjacent the cushion 20 inthe sole may be used to obstruct the stub openings. As mentioned above,although the cushion 20 may trap air once the stubs 34 are obstructed,the walls of the cushion 20 provide the main support and cushioning fora foot, instead of the trapped air or other fluid.

In addition to blow-molding, other conventional molding processes, suchas vacuum molding, extrusion, and injection molding may be used to formthe cushion of the invention. When vacuum molding a cushion, 1 or 2 bedsystems may be used. In a 1 bed system opposing surfaces of the cushionare separately formed and joined, such as by RF welding. In a 2 bedsystem, first and second molds are used to form and join opposingsurfaces of the cushion. Each inner bladder component may be formed witha different manufacturing process and/or material. For example, innerelements disposed within the lateral chambers may be formed to have alower stiffness than inner element 40 of the medial chamber.

Referring to FIGS. 6 and 7 a cushion 20′ lacks the pin marks of cushion20 but is otherwise the same. Cushion 20′ includes a lateral chamber24′, a rear chamber 28′ and a medial chamber 26′. Ribs 56′ add stiffnessto lateral and rear chambers 24′, 28′. Reference characters with primesrefer to the same characters without primes as discussed above.

Referring to FIGS. 8-11, a shoe sole 200 includes a cushion 202. A heelportion 201 of sole 200 includes a rear outsole 204 associated with arear chamber 216, a medial outsole 206 associated with a medial chamber212, and a lateral outsole associated with a lateral chamber 210. Eachoutsole may be affixed to its respective chamber, such as by adhesive.Sole 200 also includes a midsole 218, which can be formed of, forexample, EVA.

Medial chamber 212 includes an inner cushioning element, which is aninner chamber 214, such as a blow molded inner chamber, as discussedabove.

Chambers 210 and 212 move, such as by flexing, with respect to oneanother about a web 220. Rear chamber 216 moves with respect to chambers210 and 212 about a web 222, which forms a heel cleft as discussedabove.

At least a portion of cushion 202 may be exposed, that is not covered byan outsole portion, as seen in FIG. 11. The outsole may be applied tobottom surfaces of the chambers of cushion 202 without an interveningportion of midsole thereby leaving web portions of cushion 202substantially exposed.

Referring to FIGS. 12-15, a heel portion 301 of a sole 300 includes acushion 302. Cushion 302 includes a medial chamber 304 with an innercushioning element 306, a lateral chamber 308, and a rear chamber 310.

Heel portion 301 includes an outsole 312, which may be spaced apart fromcushion 302 by a midsole 314. Portions 319 of outsole 312 may containgeometric features, such as herringbone features, to facilitatetraction. A forefoot portion of sole 300 contains an outsole 321, whichmay also contain portions 323 with geometric features.

It should be understood that a cushion of the invention may be placed inthe forefoot of a shoe in order to provide cushioning, for example, tothe materials and phalanges of the foot. The forefoot chambers may bedivided into medial and lateral zones and extend along the lateral andmedial sides of the forefoot of the wearer's foot. Each chamber mayinclude an internal chamber to regulate the component's stability andcushioning characteristics. The height to width ratio of the forefootcushion chambers is preferably smaller than the corresponding ratio ofthe medial chamber of cushion 20.

While the above invention has been described with reference to certainpreferred embodiments, it should be kept in mind that the scope of thepresent invention is not limited to these. Thus, one skilled in the artmay find variations of these preferred embodiments which, nevertheless,fall within the spirit of the present invention, whose scope is definedby the claims set forth below.

1. A cushion for use in a shoe sole, comprising: a medial chamber forcushioning a medial portion of a wearer's foot; an internal chamberdisposed within the medial chamber and cooperating with the medialchamber to increase a stiffness of the medial chamber relative to the atleast one lateral chamber, an outer surface of the internal chamberaligned along an inner surface of the medial chamber to follow the shapethereof; and at least one lateral chamber for cushioning a lateralportion of the wearer's foot, wherein the at least one lateral chamberis fluidly disconnected from the medial chamber so that the medialchamber and the at least one lateral chamber are compressibleindependently from each other.
 2. The cushion of claim 1, wherein themedial chamber and the at least one lateral chamber are of unitaryconstruction.
 3. The cushion of claim 2, wherein the medial and the atleast one lateral chamber are blow molded.
 4. The cushion of claim 1,wherein the inner chamber is formed of a material having a stiffnesshigher than a stiffness of a material forming the medial and the atleast one lateral chamber.
 5. The cushion of claim 1, wherein the innerchamber is blow molded.
 6. A shoe sole comprising the cushion ofclaim
 1. 7. The cushion of claim 1, wherein the medial and the at leastone lateral chamber are spaced apart by a web, and wherein the web isarranged along a longitudinal axis of the shoe sole so that the cushionflexes about the longitudinal web.
 8. The cushion of claim 1, whereinthe medial chamber and the internal chamber are formed of a materialhaving a stiffness and strength sufficient to support the medial edge ofa wearer's foot.
 9. The cushion of claim 1, wherein the stiffness of themedial chamber is larger than that of the at least one lateral chamber.10. The cushion of claim 9, wherein the stiffness of the medial chambercooperating with the internal chamber is at least 10% greater than thatof the at least one lateral chamber.
 11. The cushion of claim 9, whereinthe stiffness of the medial chamber cooperating with the internalchamber is at least 25% greater than that of the at least one lateralchamber.
 12. The cushion of claim 1, wherein the medial chambercomprises a material having a lower modulus than a material forming theinternal chamber.
 13. The cushion of claim 1, wherein the medial chambercomprises at least one of thermoplastics including urethane and blendsthereof, PVC and blends thereof, polyester and polyester-polyetherglycol blends, ethylene vinyl acetate and polyether.
 14. The cushion ofclaim 1, wherein the internal chamber comprises at least one of apolyester elastomer including HYTREL, HTR5612 and HTX8382, urethane andblends thereof, PVC and blends thereof, polyester andpolyester-polyether glycol blends, ethylene vinyl acetate, polyether,and a closed cell foam.
 15. The cushion of claim 1, wherein a thicknessof each wall of the medial chamber and of the at least one lateralchamber is greater than or equal to 1.0 mm and less than or equal to 2.5mm.
 16. The cushion of claim 1, wherein the at least one lateral chambercomprises two or more lateral chambers in fluid connection with oneanother.
 17. The cushion of claim 1, further comprising a rear chamber,the rear chamber fluidly disconnected from the medial chamber and the atleast one lateral chamber so that the rear chamber is independentlycompressible from the medial chamber and the at least one lateralchamber.
 18. The cushion of claim 17, wherein the rear chamber is spacedapart from the medial chamber and at least one lateral chamber by aflexible web.
 19. The cushion of claim 18, wherein the rear chamber andthe flexible web are disposed at an angle from a centerline of thecushion, wherein the flexible web forms a heel cleft.
 20. The cushion ofclaim 19, wherein the angle is between 20 degrees and 45 degreesinclusive.
 21. The cushion of claim 20, wherein the medial chamberextends further toward a forefoot of the shoe sole than the at least onelateral chamber so that the cushion has an asymmetric footprint, therebyreducing the tendency of a wearer's foot to pronate.
 22. The cushion ofclaim 1, wherein the medial chamber extends further toward a forefoot ofthe shoe sole than the at least one lateral chamber so that the cushionhas an asymmetric footprint thereby reducing the tendency of a wearer'sfoot to pronate.
 23. The cushion of claim 1, wherein one of the at leastone lateral chamber comprises an internal element that is more compliantthan the internal chamber disposed within the medial chamber.
 24. Thecushion of claim 1, wherein at least one of the medial chamber and theat least one lateral chamber comprises ribs positioned on a surfacethereof, the ribs adapted to stiffen the respective chamber.
 25. Thecushion of claim 1, the internal chamber comprising an outer surfacehaving stiffening ribs and the medial chamber comprising locator marksfor holding the internal chamber in a predetermined position within themedial chamber, wherein the marks are formed as depressions extendingfrom an outer surface of the medial chamber to an outer surface of theinner chamber, and are of complementary shape and positioning relativeto the ribs.